Battery element, a battery and a method for forming a battery

ABSTRACT

A battery element includes a substrate with a plurality of trenches extending into the substrate. At least a part of each trench of the plurality of trenches is filled with a solid state battery structure. Further, the battery element includes a front side battery element electrode arranged at a front side of the substrate and electrically connected to a first electrode layer of the solid state battery structures within the plurality of trenches. Additionally, the battery element includes a backside battery element electrode arranged at a backside of the substrate and electrically connected to a second electrode layer of the solid state battery structures within the plurality of trenches.

TECHNICAL FIELD

Embodiments relate to energy storage devices and in particular to abattery, a battery element and a method for forming a battery.

BACKGROUND

With the increased use of portable electronic devices such as notebooks,portable telephones, cameras and others and with the increased use ofelectrically-driven automobiles, secondary or rechargeable batterieswith high energy density have received increasing attention as a powersource for these devices. Examples of such rechargeable batteries arelithium ion rechargeable batteries.

The demand for energy storage devices is further growing due to agrowing production volume for electric vehicles and growing demand tostore energy (e.g., renewable energy).

Energy density, i.e., how much energy can be stored in a battery, isimportant to reduce the weight and therefore the cost of batterymaterials and cost of battery movement. Therefore, it is of generalinterest to increase the energy density of batteries.

SUMMARY OF THE INVENTION

Some embodiments relate to a battery element comprising a substrate witha plurality of trenches reaching into the substrate. At least a part ofeach trench of the plurality of trenches is filled with a solid statebattery structure. Further, the battery element comprises a front sidebattery element electrode arranged at a front side of the substrate andelectrically connected to a first electrode layer of the solid statebattery structures within the plurality of trenches. Additionally, thebattery element comprises a backside battery element electrode arrangedat a backside of the substrate and electrically connected to a secondelectrode layer of the solid state battery structures within theplurality of trenches.

Further embodiments relate to a method for forming a battery comprisingetching trenches into a substrate and forming a solid state batterystructure within the trenches. Further, the method comprises forming afront side battery element electrode arranged at a front side of thesubstrate and electrically connected to a first electrode layer of thesolid state battery structure within the trenches. Additionally, themethod comprises forming a backside battery element electrode arrangedat a backside of the substrate and electrically connected to a secondelectrode layer of the solid state battery structure within thetrenches.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of apparatuses and/or methods will be described in thefollowing by way of example only, and with reference to the accompanyingfigures, in which

FIG. 1 shows a schematic cross section of a battery;

FIG. 2 shows a schematic cross section of a battery element withcavities;

FIG. 3 shows a schematic cross section of another battery element withcavities;

FIG. 4 shows a flow chart of a method for forming a battery;

FIG. 5 shows a schematic cross section of a battery element withbackside electrode;

FIG. 6 shows a schematic cross section of another battery element withbackside electrode;

FIG. 7 shows a schematic cross section of a battery with a batteryelement stack;

FIG. 8 shows schematic cross sections of battery element stacks;

FIG. 9 shows a flow chart of a method for forming a battery;

FIG. 10a-10c show schematic cross sections during forming a batteryelement;

FIG. 11a-11c show schematic cross sections during forming anotherbattery element;

FIG. 12 shows a flow chart of a method for forming a battery element;

FIG. 13a-13c show schematic top views during forming a battery element;

FIG. 14a-14c show schematic top views during forming another batteryelement;

FIG. 15 shows a schematic top view of a wafer and two possibledistributions of trenches;

FIG. 16a shows a schematic cross section of a battery element withquadratic trenches;

FIG. 16b shows a schematic top view of the battery element shown in FIG.16a ; and

FIG. 17 shows a schematic cross section of a battery with a stack ofbattery elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Various example embodiments will now be described more fully withreference to the accompanying drawings in which some example embodimentsare illustrated. In the figures, the thicknesses of lines, layers and/orregions may be exaggerated for clarity.

Accordingly, while further embodiments are capable of variousmodifications and alternative forms, some example embodiments thereofare shown by way of example in the figures and will herein be describedin detail. It should be understood, however, that there is no intent tolimit example embodiments to the particular forms disclosed, but on thecontrary, example embodiments are to cover all modifications,equivalents, and alternatives falling within the scope of thedisclosure. Like numbers refer to like or similar elements throughoutthe description of the figures.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.).

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of furtherexample embodiments. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises,” “comprising,” “includes” and/or “including,” whenused herein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, e.g., those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1 shows a schematic cross section of a battery 100 according to anembodiment. The battery 100 comprises two externally accessible batteryelectrodes 102 to provide a supply voltage to a connectable device.Further, the battery 100 comprises at least more than half of a wafer110 comprising two wafer electrodes 112. The battery 100 can be formedin a substrate having a main surface with a surface area of at least 600cm². For example, if a 200 nm wafer (where the diameter is 200 nm) isused, at least a more than half of the wafer would be about this size(e.g., about π R²). Using substantially all of a 200 nm wafer wouldproduce a substrate of about 1200 cm² while using all of a 450 nm waferwould produce a substrate of about 6350 cm². Accordingly, in certainembodiments, the substrate size is between 1200 cm² and 6350 cm². Inother embodiments, the substrate can be bigger or smaller.

The wafer comprises a plurality of trenches 114 reaching from a surfaceof the wafer 110 into the wafer 110. At least a part of a trench 114 (orof each trench) of the plurality of trenches 114 is filled with a solidstate battery structure 116. The solid state battery structure 116within the trench 114 comprises electrodes electrically connected to thewafer electrodes 112.

By using large parts of a wafer or the complete wafer directly forforming a battery, high energy densities may be reached with low cost,since a wafer can be handled in one piece during manufacturing. Further,no or only few space of the wafer may be lost for areas used for cuttingthe wafer. Further, the manufacturing time and costs for cutting thewafer can be kept low or may be completely avoided.

The battery 100 is a rechargeable battery (or a non-rechargeablebattery) providing a supply voltage at the two externally accessiblebattery electrodes 102 (e.g., anode and cathode). An external device(e.g., electric vehicle, a power supply network, a machine or otherelectronic devices) may be connected to the two externally accessiblebattery electrodes 102. Further, an external energy generator or powersupply network may be connected or connectable to the battery 100 forrecharge.

For example, the two externally accessible battery electrodes 102 mayreach through a package of the battery 100. The package may surround theat least more than half of a wafer 110 to protect the at least more thanhalf of a wafer 110 against undesired environmental influences.

The at least more than half of a wafer 110 may be a large part (morethan 50%, more than 70%, more than 80% or more than 90%) of a wafer orsubstantially a complete wafer comprising the two wafer electrodes 112.Using a complete wafer may provide a large energy density, while lowmanufacturing effort may be required (e.g., cutting and waste may beavoided). Alternatively, another geometry of the wafer or the batterymay be desired. For example, the wafer may be cut to a quadratic orrectangular shape with still more than half of the original wafer size.In the following, the term wafer may mean at least more than half of awafer or a complete wafer.

The wafer 110 may represent a battery element or battery cell of thebattery 100. The wafer 110 can provide an electrical voltage at thewafer electrode due to the solid state battery structures implemented onthe wafer 110. In other words, a battery element may be part of abattery and may be able to provide a voltage (stored energy) atelectrodes. The battery 100 may at least further comprise a packageprotecting the battery element. Optionally, the battery 100 may comprisemore than one battery element (e.g., wafers with solid state batterystructures in trenches). In other words, the battery 100 may optionallycomprise a plurality of at least more than half wafers with trenchescomprising solid state battery structures.

The two wafer electrodes 112 (e.g., anode and cathode) may provide theenergy stored by the battery structures 116 of the wafer 110 and may beconnected to the two externally accessible battery electrodes 102, tothe wafer electrodes of other wafers or battery elements of the batteryor to a control circuit of the battery (e.g., for controlling a supplyvoltage or supply current provided by the battery).

A control circuit (e.g., for controlling a supply voltage or supplycurrent provided by the battery or determining a remaining charge or acharge status) may be integrated on the wafer 110 or may be arrangedbetween the two wafer electrodes 112 and the two externally accessiblebattery electrodes 102 (e.g., on a separate semiconductor die).Optionally, the control circuit may provide a signal (e.g., indicating aremaining charge of the battery) to an optional further externallyaccessible battery electrode of the battery 100 or may receive a controlsignal (e.g., triggering a control of a supply voltage or supply currentprovided by the battery) from an optional further externally accessiblebattery electrode of the battery 100.

The wafer 110 may be a semiconductor wafer (e.g., silicon based wafer,silicon carbide based wafer, gallium arsenide based wafer), a glasswafer or another wafer suitable for forming trenches 114 with solidstate battery structures.

The wafer 110 comprises a plurality of trenches 114 etched into thesubstrate. The trenches may be etched into the wafer 110 starting from asurface of the wafer 110 until a desired depth is reached.

For example, some or all trenches 114 of the plurality of trenches 114may reach deeper into the wafer 100 than 500 μm (or deeper than 700 μmor deeper than 800 μm) or may reach through the whole wafer 100 (e.g.,wafer with thickness of 750 μm for a diameter of 200 mm or 880 μm for adiameter of 300 mm).

For example, some or all trenches 114 of the plurality of trenches 114may comprise a maximal depth larger than a maximal lateral dimension.For example, some or all trenches 114 of the plurality of trenches 114may comprise an aspect ratio larger than 10 (or larger than 20 or largerthan 30). By increasing the aspect ratio, the surface for forming solidstate battery structures may be increased resulting in a higher energydensity.

Optionally, some or all trenches 114 of the plurality of trenches 114may comprise a maximal width of less than 300 μm (or less than 200 μm orbetween 5 μm and 200 μm, for example, 40 μm). The maximal width may be amaximal lateral extension of the trench 114 at the surface of the wafer100, for example. By implementing narrow trenches 114, a number oftrenches manufacturable on the wafer 100 may be increased.

For example, some or all (except at the edge) trenches of the pluralityof trenches may comprise a distance to each other (a distance toneighboring trenches or to the closest neighboring trench) between 2 μmand 300 nm (or between 1 μm and 500 nm). By implementing trenches withsmall distance to each other, a number of trenches manufacturable on thewafer may be increased. Keeping the distance between trenches above apredefined limit may increase the stability of the wafer 100.

At least a part of a trench 114, of some trenches or all trenches of theplurality of trenches 114 is filled with a solid state battery structure116. The solid state battery structure 116 within the trench 114, sometrenches or all trenches of the plurality of trenches 114 compriseselectrodes or electrode layers electrically connected to the waferelectrodes 112. A solid state battery structure 116 may be a batterystructure within one trench or may extend over several trenches of theplurality of trenches 114 or all trenches 114 of the plurality oftrenches 114. Optionally, a solid state battery structure may beimplemented in several or each trench and the electrodes of the solidstate battery structures 116 may be connected or coupled to each other.A solid state battery structure 116 extending over several trenches maybe obtained by simultaneously forming solid state battery structures 116within these trenches.

The solid state battery structure 114 within the trench or withinseveral or all trenches may comprise a solid state electrolyte layerbetween a first electrode layer connected to a first wafer electrode ofthe two wafer electrodes and a second electrode layer connected to asecond wafer electrode of the two wafer electrodes, for example. Inother words, an anode layer of the solid state battery structure 114 maybe connected or coupled to (e.g., through a control circuit or othersolid state battery structures) an anode electrode of the wafer 110 anda cathode layer of the solid state battery structure 114 may beconnected or coupled to a cathode electrode of the wafer 110.

For example, the solid state electrolyte layer may comprise or mayconsist of lithium phosphorus oxynitride LiPON or another solid stateelectrolyte.

Alternatively or additionally, the electrolyte layer may comprise or mayconsist of at least one material of the following group of materials,the group including: lithium, phosphorus, lanthanum, titanium, lithiumphosphorus oxynitride, lithium lanthanum titanium oxide (LLTO), apolymer, poly oxyethylene, LiPO_(1 x)N_(1 y), thio-LISICON materials(lithium superionic conductor, e.g., Li₁₀GeP₂S₁₂ orLi_(x)Ge_(y)P_(z)S₄), Li_(x)M_(1−y)M′_(y)S₄ (M=Si or Ge, and M′=P, Al,Zn, Ga, or Sb), Li_(x)Al_(y)Ti_(z)(PO₄), Silicon Oxide (SiO₂), SiliconNitride Si₃N₄ or any other suitable electrolyte, e.g., sodium super ionconductors (NASICON), NASICON type materials (e.g.,Na_(1+x+4y)M_(2−y)Si_(x)P_(3−x)O₁₂, 0≦x≦3, 0≦y≦1 (M=Ti, Hf, or Zr)),Li₂S P₂S₅, Li₂S P₂S₅ SiS₂, Li₂S SiS₂, or oxysulfide glass (e.g.,[[Li₂S]_(0.6)[SiS₂]_(0.4)]_(1−x)[Li_(x)MO_(y)]_(x) (M=Si, P, Ge, B, Al,Ga, In)). A solid state electrolyte may be regarded as a material whichmay transport electrical charge due to the movement of ions in thematerial, e.g., through channels, voids, or empty crystallographicpositions in their crystal structure.

Optionally, the first electrode layer may comprise an anode layer (e.g.,comprising or consisting of carbon or silicon) and optionally acollector layer (e.g., comprising or consisting of titan nitride TiN).The collector layer may be also arranged within the trench or may coverone or more trenches being in contact with the anode layer at thesurface of the wafer, for example.

Alternatively or additionally, the anode layer may comprise silicon,polysilicon, amorphous silicon, carbon, amorphous carbon, graphite,Li₄Ti₅O₁₂ (LTO), CuN₃, titanium oxide (TiO₂), or any other suitableanode material, as for example titanium, a metal silicide (e.g., calciumsilicide, magnesium silicide, molybdenum silicide), Li₁₅Si₄, a lithiumcontaining alloy (e.g., Li₂₂M₅/M (M=Ge, Sn, Pb, Si)), Li_(4.4)Si,Li_(4.4)Ge, tin-oxide based glasses (e.g., SnO—B₂O₃—P₂O₅—Al₂O₃),SnS—P₂S₅, Li₂S—P₂S₅, silicon containing transition metal nitrides (e.g.,SiMxNy (M=Co, Ni, Cu)), Ni coated by TiO₂, Sn, Ge, Al, Pb, In, ZnO. Theanode may be defined herein, for example, as the negative electrodeduring charge of the battery. According to various embodiments, theanode may include a mixture of anode materials (as described before) ora mixture of an anode material with another additional material toprovide a micro-composite material as anode material.

Further, the second electrode layer may comprise a cathode layer (e.g.,comprising or consisting of lithium cobalt oxide LiCoO₂) and optionallya collector layer (e.g., comprising or consisting of titan nitride).

Alternatively or additionally, the cathode layer may comprise lithium,cobalt, nickel, aluminum, oxygen, iron, phosphorous, sulfur, manganese,vanadium, manganese spinel, lithium nickel manganese cobalt, lithiumiron phosphate (doped or undoped), transition metal oxides (e.g., MnO₂,Fe₃O₄, Co₃O₄, TiO₂, NiO), olivine (e.g., LiCoPO₄), LiCoO₂, LiNiO₂,LiNi_(x)Mn_(y)O₂, LiNi_(1−x)Co_(x)O₂, LiNi_(0.85)Co_(0.1)Al_(0.05)O₂,LiNi_(0.33)Co_(0.33)Mn_(0.33)O₂, LiMn₂O₄ (spinel structure),Li_(4/3)Ti_(5/3)O₄, V₂O₅, amorphous V₂O₅, LiMn₂O₄, Li₂S, and LiFePO₄, orany other suitable cathode material, e.g., including nickel or stainlesssteel. The cathode may be defined herein, for example, as the positiveelectrode during charge of the battery.

Alternatively or additionally, one or both collector layers may compriseCu, TiN, Pt, Al, AlCu, W, Au, WN, Carbon or compositions or alloys ofthese materials.

In some embodiments, a trench, some trenches or all trenches of theplurality of trenches comprise a cavity. In other words, the solid statebattery structure may be formed on the walls of one, some or alltrenches leaving an air gap in the middle of the trenches. Afterwards,the air gap may be covered by another layer (e.g., metal layer forimplementing an electrode of the wafer or the anode layer mentionedabove) leaving a cavity within one, some or all trenches of theplurality of trenches.

A cavity within a trench may provide space for an expansion of the solidstate battery structure during charging and/or discharging. Therefore,mechanical stress within the at least more than half of a wafer 110 dueto the expansion process may be significantly reduced by implementingcavities within the trenches.

A cavity may be formed or kept within all trenches comprising a solidstate battery structure. In this way, the mechanical stress may be keptvery low. Alternatively, it may be sufficient to form or keep a cavityin every second or third (or another number) trench in order to reducethe mechanical stress to a desired level.

FIG. 2 shows a schematic cross section of a battery element 200according to an embodiment. The battery element 200 (or battery cell)comprises a substrate 210 with a plurality of trenches 212 reaching intothe substrate 210. A part of a trench 212 (or some or all trenches) ofthe plurality of trenches 212 is filled with a solid state batterystructure 214. Further, the trench 212 (or some or all trenches) of theplurality of trenches 212 comprises a cavity 216.

A cavity 216 within a trench may provide space for an expansion of thesolid state battery structure during charging and/or discharging asmentioned above.

The substrate 210 may be a small die, a large part of a wafer or acomplete wafer, for example. The substrate 210 may be a semiconductorsubstrate (e.g., silicon based, silicon carbide based, gallium arsenidebased), a glass substrate or another substrate suitable for formingtrenches 114 with solid state battery structures.

Optionally, a part of each trench of the plurality of trenches is filledwith a solid state battery structure and optionally each trench of theplurality of trenches comprises a cavity.

The battery element 200 may comprise one or more optional additionalfeatures corresponding to one or more aspects described in connectionwith the proposed concept or one or more embodiments (e.g., FIG. 1)described above (e.g., dimension of trenches, solid state batterystructure, electrodes, package).

FIG. 3 shows a schematic cross section of a battery element 300according to an embodiment. The implementation of the battery element300 is similar to the battery element shown in FIG. 2. The solid statebattery structure within the trenches 214 (e.g., trench cells) comprisesa solid state electrolyte layer 306 between a first electrode layer anda second electrode layer. The solid state electrolyte layer 306 maycomprise or may consist of lithium phosphorus oxynitride LiPON. Further,the first electrode layer may comprise an anode layer 308 (−) (e.g.,comprising or consisting of carbon or silicon). A current collectorlayer 310 (−) (e.g., comprising or consisting of titan nitride TiN) mayextend over several or all trenches. The current collector layer 310 maycover the openings of the trenches and may seal the cavity 216 remainingwithin the trenches 214. Further, the second electrode layer maycomprise a cathode layer 304 (+) (e.g., comprising or consisting oflithium cobalt oxide LiCoO2) and a current collector layer 302 (+)(e.g., comprising or consisting of titan nitride). The current collectorlayer 310 of the first electrode layer may be connected or coupled to ananode battery element electrode (e.g., anode wafer electrode) and thecurrent collector layer 302 of the second electrode layer may beconnected or coupled to a cathode battery element electrode (e.g.,cathode wafer electrode).

The first electrode layer and the second electrode layer may beelectrically connectable at the same side of the substrate. For example,the other layers of the solid state battery structure may be removed ata contact area 320 for providing access to the second electrode layer.Alternatively, the first electrode layer and the second electrode layermay be connectable at different sides of the substrate (e.g., FIGS. 5and 6).

The battery element or structure may be manufacturable or manufacturedwith semiconductor processes mainly or only, for example. Some newmaterials may be used (e.g., deposited) in connection with thesemiconductor processes.

The battery element 300 may comprise one or more optional additionalfeatures corresponding to one or more aspects described in connectionwith the proposed concept or one or more embodiments (e.g., FIG. 1 or 2)described above (e.g., dimension of trenches, solid state batterystructure, electrodes, package, cavity).

Some embodiments relate to a mobile device comprising a casingaccommodating an electronic device configured to provide at least one ofaudio data and video data for a user and a battery configured to providea power supply for the electronic device. The battery comprises abattery element comprising a substrate with a plurality of trenchesreaching into the substrate. A part of a trench of the plurality oftrenches is filled with a solid state battery structure. The substratecomprises maximal dimension larger than a maximal dimension of thecasing of the mobile device.

Due to the usage of large substrates, the battery size can be adapted tothe size of the mobile device. In this way, an efficient power supplyfor mobile devices may be provided.

A mobile device may be a smart phone, a laptop or a tablet, for example.

A maximal dimension of a casing of may be an extension of the casing ina direction of a largest dimension of the casing. For example, for asubstantially rectangular casing, the maximal dimension may be thediagonal of the rectangle. In other words, the substrate may comprise ageometry having a maximal dimension (e.g., diagonal of a rectangle)being larger than at least half (or at least 70% or at least 80%) of amaximal dimension of the casing of the mobile device.

More details or aspects regarding the battery, the battery element, thesubstrate, the trenches and/or the solid state battery structure arementioned in connection with the proposed concept or one or moreembodiments described above.

FIG. 4 shows a flow chart of a method 400 for forming a batteryaccording to an embodiment. The method 400 comprises preparing 410 awafer comprising (at least) two wafer electrodes. The wafer comprises aplurality of trenches reaching from a surface of the wafer into thewafer. At least a part of a trench of the plurality of trenches isfilled with a solid state battery structure. Further, the solid statebattery structures within the trenches comprise electrodes electricallyconnected to the wafer electrodes. Additionally, the method 400comprises forming 420 a battery package comprising two externallyaccessible battery electrodes to provide a supply voltage to aconnectable device.

By using a wafer (e.g., substantially the complete wafer) directly forforming a battery, high energy densities may be reached with low cost,since a wafer can be handled in one piece during manufacturing. Further,no or only few space of the wafer may be lost for areas used for cuttingthe wafer. Further, the manufacturing time and costs for cutting thewafer can be kept low or may be completely avoided.

Preparing 410 the wafer may comprise forming trenches, solid statebattery structures and wafer electrodes on the wafer and/or may comprisepreparing (e.g., cleaning, positioning) the wafer for forming 420 thebattery package.

For example, the complete wafer may be used for the battery and may beimplemented in the battery package. Alternatively, the method 400 maycomprise cutting the wafer to obtain a remaining part of the wafer witha desired geometry. The remaining part of the wafer may be at least morethan half of the wafer and may comprise the two wafer electrodes. Inthis way, a battery with a desired geometry and/or size may be provided.

The method 400 may comprise one or more optional additional actscorresponding to one or more aspects described in connection with theproposed concept or one or more embodiments (e.g., FIG. 1-3) describedabove (e.g., dimension of trenches, solid state battery structure,electrodes, package, cavity).

Some embodiments relate to a wafer battery. Such wafer batteries may beintegrated or implemented in battery packs comprising battery cells(e.g., wafer batteries), wiring and assembly parts and at least onebattery management system BMS, for example.

A wafer battery or battery comprising battery structures implemented onwafers may replace pouch cells for several reasons. Wafers withdiameters of 100 mm, 150 mm, 200 mm, 300 mm or 450 mm or larger may beused. Semiconductor tools and process may be used, for example, topattern the surface. Real 3D battery design may become possible. Forexample, energy density and power density can be influenced by patternfeature sizes. Higher energy density than with a pouch cell may beachievable. Also higher power density than pouch cells, depending onmaterial choice and pattern feature sizes, may be achievable, forexample. Trenches with ˜AR 30 (aspect ratio of 30) or higher may providehigher power density than pouch cells, for example. Existing(manufacturing) tools may be used, e.g., etching 300 mm tools. Assumingsame energy content, the weight of the battery may be reduced by factorof at least 2, for example.

For example, ready processed wafer=system (e.g., combing carrierfunction and active battery parts) may be obtained. Because of 3D designboth, high specific energy densities and specific power densities may beachieved.

A proposed (solid state) battery may be used as traction battery for EV(electric vehicle, car) or storage device for energy (e.g., renewableenergies, for example, solar energy), for example.

The proposed concept may be enabled by the capability of forming deeptrenches (e.g., on 300 mm wafers), for example.

By using the proposed concept, a micro battery may be integrated into anASIC (Application Specific Integrated Circuit). Solid state batteriesmay be stacked for cars and/or energy storage applications. For example,an electric vehicle may comprise same or similar weight with more range(e.g., more than two times, three times or four times higher).

Semiconductor processes may be used for fabrication. New materials maybe introduced into the process chain (e.g., LiPON, LiCo_(x)O_(y)), forexample.

A proposed battery may be a (smart) battery comprising an embeddedcontroller (e.g., control circuit mentioned above).

The surface of the wafer may be enlarged through trench usage. Further,the semiconductor pattering may allow a flexible wiring. In this way,faster load cycles may be achievable.

The energy density on battery block level may be compared betweendifferent used materials. For example, a wafer battery based on LiCoO2(lithium cobalt oxide) and carbon may comprise a weight of approximately80 kg (e.g., whole system with cells, assembly and cooling) for 16 KWh(or ˜44 kg for active cells) resulting in a specific energy density ofapproximately 190 Wh/kg. For example, a wafer battery based on LiS(lithium sulfur) and Si (silicon) may comprise a weight of approximately45 kg (e.g., whole system with cells, assembly and cooling) for 16 KWh(or ˜17 kg for active cells) resulting in a specific energy density ofapproximately 360 Wh/kg. A weight reduction of more than 75% may beachievable.

Further, the power density (e.g., power delivered by the engine, W/kg)may be increased by implementing the proposed concept.

FIG. 5 shows a schematic cross section of a battery element 500according to an embodiment. The battery element 500 (or battery cell)comprises a substrate 510 with a plurality of trenches 512 reaching froma surface of the substrate 510 into the substrate 510. At least a partof each trench 512 of the plurality of trenches 512 is filled with asolid state battery structure. Further, the battery element 500comprises a front side battery element electrode 520 arranged at a frontside of the substrate 510 and electrically connected or connectable to afirst electrode layer 514 of the solid state battery structures withinthe plurality of trenches 512. Additionally, the battery element 500comprises a backside battery element electrode 530 arranged at abackside of the substrate 510 and electrically connected or connectableto a second electrode layer 516 of the solid state battery structureswithin the plurality of trenches 512.

A battery element with electrodes (anode and cathode) at opposite sidesof a substrate may be integrated in a battery with low effort, since theelectrodes are easily accessible at both sides of the battery element.Further, several battery elements with front side and backside electrodemay be stacked with low effort. Therefore, a battery with high energydensity may be obtainable.

The battery element 500 or battery cell may be used for forming abattery. The battery element 500 can provide an electrical voltage atthe front side battery element electrode 520 and the backside batteryelement electrode 530 due to the one or more solid state batterystructures implemented on the substrate 510. In other words, a batteryelement 500 may integrated in a battery and is able to provide storedenergy at electrodes. For example, a battery may at least comprise apackage protecting at least one battery element 500. Optionally, abattery may comprise more than one battery element (e.g., substrate withsolid state battery structures in trenches).

The substrate 510 may be a small die, a large part of a wafer or acomplete wafer, for example. The substrate 510 may be a semiconductorsubstrate (e.g., silicon based, silicon carbide based, gallium arsenidebased), a glass substrate or another substrate suitable for formingtrenches 512 with solid state battery structures.

The front side of the substrate 510 may be the side of the substrate 510used for starting etching the trenches 512 into the substrate 510 and/orthe side of the substrate 510 used for depositing the solid statebattery structure, for example. The backside of the substrate 510 may bethe side of the substrate 510 located opposite to the front side.

The front side battery element electrode 520 may be a contact area,contact structure or contact layer accessible at the front side of thesubstrate 510. In other words, the front side battery element electrode520 may enable an electrical connection or may implement an interface toanother device, a battery electrode or another battery element at thefront side of the substrate 510. For example, the front side batteryelement electrode 520 may be a contact layer extending along at least ahalf of the front side (or at least 70%, at least 80% or at least 90%)of the substrate 510.

The backside battery element electrode 530 may be a contact area,contact structure or contact layer accessible at the backside of thesubstrate 510. In other words, the backside battery element electrode530 may enable an electrical connection or may implement an interface toanother device, a battery electrode or another battery element at thebackside of the substrate 510. For example, the backside battery elementelectrode 530 may be a contact layer extending along at least a half ofthe backside (or at least 70%, at least 80% or at least 90%) of thesubstrate 510.

The front side battery element electrode 520 and/or the backside batteryelement electrode 530 may comprise or consist of copper, aluminum, goldor another material (e.g., alloy) suitable for providing a reliablecontact interface.

For example, the trenches 512 of the plurality of trenches 512 reachfrom the front side of the substrate to the backside of the substrate.In other words, the trenches 512 may reach through the whole substrate510. In this way, the second electrode layer of the solid state batterystructures within the plurality of trenches can be electricallyconnected to the backside battery element electrode 530 with low effort,for example. Alternatively, a through silicon via may be etched from thebackside of the substrate 510 to the second electrode layer of the solidstate battery structures within the plurality of trenches to enable anelectrical contact at the backside, for example.

More details and optional aspects of the battery element 500 aredescribed in connection with the proposed concept or one or moreembodiments (e.g., FIG. 1-4) described above (e.g., substrate, dimensionof trenches, solid state battery structure, electrodes, package).

For example, the solid state battery structures within the trenches 512may comprise a solid state electrolyte layer between the first electrodelayer 514 and the second electrode layer 516. The solid stateelectrolyte layer may comprise lithium phosphorus oxynitride. The firstelectrode layer 514 may comprise an anode layer comprising carbon orsilicon. The second electrode layer 516 may comprise a cathode layercomprising lithium cobalt oxide and a collector layer comprising titannitride.

For example, the substrate 510 may comprise a thickness of more than 500μm. The trenches of the plurality of trenches 512 may comprise an aspectratio larger than 10. The trenches of the plurality of trenches maycomprise a maximal width of less than 300 μm. The trenches of theplurality of trenches may comprise a distance to each other between 2 μmand 300 nm. The trenches of the plurality of trenches may comprise amaximal depth larger than a maximal lateral dimension. Optionally, thesubstrate is substantially a complete wafer.

FIG. 6 shows a schematic cross section of a battery element 600according to an embodiment. The implementation of the battery element600 is similar to the battery element shown in FIG. 5. The solid statebattery structure within the trenches 512 (e.g., trench cells) comprisesa solid state electrolyte layer 606 between the first electrode layerand the second electrode layer. The solid state electrolyte layer 606may comprise or may consist of lithium phosphorus oxynitride LiPON.Further, the first electrode layer may comprise an anode layer 608 (−)(e.g., comprising or consisting of carbon or silicon). A currentcollector layer 620 (−) (e.g., comprising or consisting of titan nitrideTiN) may extend over several or all trenches. The current collectorlayer 620 may cover the openings of the trenches and may seal the cavity616 remaining within the trenches 214. Further, the second electrodelayer may comprise a cathode layer 604 (+) (e.g., comprising orconsisting of lithium cobalt oxide LiCoO₂) and a current collector layer602 (+) (e.g., comprising or consisting of titan nitride). The firstelectrode layer of the solid state battery structure is at least partlycovered by the front side battery element electrode 520 (e.g.,comprising or consist of copper). Further, parts of the second electrodelayer of the solid state battery structure located at the bottom of thetrenches 512 are at least partly covered by the backside battery elementelectrode 530 (e.g., comprising or consist of copper).

The current collector layer 620 of the first electrode layer may be incontact, connected or coupled to an anode battery element electrode(e.g., anode electrode) through the front side battery element electrode520 and the current collector layer 602 of the second electrode layermay be in contact, connected or coupled to a cathode battery elementelectrode (e.g., cathode electrode) through the backside battery elementelectrode 530.

The battery element 600 may comprise one or more optional additionalfeatures corresponding to one or more aspects described in connectionwith the proposed concept or one or more embodiments (e.g., FIG. 1-5)described above (e.g., dimension of trenches, solid state batterystructure, electrodes, package, cavity).

FIG. 7 shows a schematic cross section of a battery 700 according to anembodiment. The battery 700 comprises a plurality of battery elementsaccording the proposed concept or one or more embodiments (e.g., FIG.1-6) described above arranged in a stacked manner.

By stacking a plurality of proposed battery elements, a batteryproviding a desired voltage or desired capacity may be feasible. Thebattery elements may be stacked with low effort, due to the electrodesarranged on opposite sides of the substrate. In this way, a battery withhigh power density may be obtained.

The battery 700 may comprise one or more stacks of battery elements 500.The one or more stacks may be encapsulated by a battery package 710.Further, the one or more stacks may be connected or connectable toexternally accessible battery electrodes 702.

FIG. 8 shows schematic illustrations of possible battery element stacks.For example, a battery element 800 may comprise a structured wafer(e.g., structured by trenches comprising solid state battery structures)and a front side electrode (e.g., +) and a backside electrode (e.g., −)providing 4V and 30 Ah.

In an example, four such battery elements 800 may be stacked so thatfront side electrodes are in contact with backside electrodes resultingin a stack providing 16V and 30 Ah between a positive + electrode 812and a negative − electrode 814 of the stack.

Alternatively, four such battery elements 800 may be stacked so thatfront side electrodes are in contact with front side electrodes andbackside side electrodes are in contact with backside electrodesresulting in a stack providing 4V and 120 Ah between a positiveelectrode 824 and a negative electrode 822 of the stack.

For example, a battery pack for an electric vehicle with a supplyvoltage of 360-380V may be implemented by stacking proposed batteryelements.

FIG. 9 shows a flow chart of a method 900 for forming a batteryaccording to an embodiment. The method 900 comprises etching 910trenches into a substrate and forming 920 a solid state batterystructure within the trenches. Further, the method 900 comprises forming930 a front side battery element electrode arranged at a front side ofthe substrate and electrically connected or connectable to a firstelectrode layer of the solid state battery structure within thetrenches. Additionally, the method 900 comprises forming 940 a backsidebattery element electrode arranged at a backside of the substrate andelectrically connected or connectable to a second electrode layer of thesolid state battery structure within the trenches.

A battery element with electrodes (anode and cathode) at opposite sidesof a substrate may be formed with low effort, since the electrodes areeasily accessible at both sides of the battery element.

For example, a wafer (substrate) may be the carrier for the structures.One electrode on one surface may be forming a comb structure into thewafer, the other electrode on the backside may be forming acomplementary comb structure on the other side. In between, the batterylayers may be located.

Optionally, the method 900 may comprises depositing an auxiliary layerat the backside of the substrate before etching the trenches. Then thetrenches may be etched through the substrate until the auxiliary layeris reached. The auxiliary layer may be removed after forming the solidstate battery structure within the trenches to uncover the secondelectrode layer at the backside of the substrate. The auxiliary layermay provide an etch stop for the trench etch and/or may increase themechanical stability during manufacturing.

FIG. 10a-c shows an example for forming or processing a battery orbattery element with an auxiliary layer at the backside. FIG. 10a showsa deposition of an auxiliary layer 1020 (e.g., stop layer comprising orconsist of silicon nitride) on the backside of the substrate 510 (e.g.,wafer). In this way, a stop layer for a silicon Si etch may be provided.Afterwards, a battery formation (forming of solid state batterystructure) may be performed (at a front side) on the substrate 510 asshown in FIG. 10b (see also FIG. 5-6). Then, the auxiliary layer 1020(e.g., nitride) is removed on the backside and a front side/backside(metal) electrode 520, 530 is formed as shown in FIG. 10 c.

In other words, a proposed structure may be formed by a substrate (e.g.,like a silicon wafer), a nitride deposition on the backside ofsubstrate, a battery formation (e.g., etching trenches in silicon,deposition of bottom electrode layer, deposition of battery layers likesolid electrolyte etc., deposition of top electrode layer), removingbackside nitride and deposition of metal electrode on front side andbackside, for example.

Alternatively, the method 900 may comprise thinning the substrate fromthe backside of the substrate after forming the solid state batterystructure within the trenches until the second electrode layer isuncovered at the backside of the substrate.

FIG. 10a-c shows an example for forming or processing a battery orbattery element by thinning the substrate from the backside. FIG. 11ashows a substrate 510 (e.g., wafer). A battery formation (forming ofsolid state battery structure) may be formed (at a front side) on thesubstrate 510 as shown in FIG. 11b (see also FIG. 5-6). Then, a backsidepolish (e.g., thinning film technology) to the bottom electrode (of thesolid state battery structure) may be performed and a frontside/backside (metal) electrode 520, 530 is formed as shown in FIG. 11c.

In other words, a proposed structure may be formed by a substrate (e.g.,like a silicon wafer), battery formation (e.g., etching trenches insilicon, deposition of bottom electrode layer, deposition of batterylayers like solid electrolyte etc., deposition of top electrode layer),wafer thinning until stop on bottom electrode and deposition of metalelectrode on front side and backside, for example.

Each wafer may comprises a top electrode on the one wafer surface, whichcan be chosen in thickness independently of the layers in theelectrolyte, and a bottom electrode, which can also be chosenindependently, and both can be chosen independently in thickness of thelayers in the trenches required for the battery, for example.

Optionally, the method 900 may comprise stacking a plurality of batteryelements so that the electrodes of neighboring battery elements are incontact with each other.

The batteries or battery elements comprising wafer may be easily stackedeither to form a battery with higher voltage (+/−, +/−, +/−, etc.) or toform batteries with higher capacity (+/−, −/+, +/−, −/+, etc.) or both(e.g., FIG. 7-8).

The method 900 may comprise one or more optional additional actscorresponding to one or more aspects described in connection with theproposed concept or one or more embodiments (e.g., FIG. 1-8) describedabove (e.g., dimension of trenches, solid state battery structure,electrodes, package, cavity).

Some embodiments relate to a battery pack. A proposed battery design mayenable to get the current out over a low ohmic path. This may beimportant for Power density, e.g., to get small charging times and toget high peak power out of the battery. In the proposed setup mentionedabove, two contacts are made on the front side to contact the twoelectrode layers, for example. The thickness of the bottom layer may belimiting the current by its series resistance.

According to a proposed aspect, wafer backside processing may be used tocontact the bottom electrode from the backside (3-D structure). This mayenable very low ohmic paths to the solid state electrolyte. In addition,the electrode on the surface can be made thicker than in the trenches,which may help to increase the conductivity further for more powerdensity. As the wafers may have one electrode on the one surface and oneon the other, it is easy to stack the wafers to form either highercurrent capability or to form batteries with higher voltage, forexample.

According to a proposed aspect, a battery may be formed with a wafer,where the front side of the wafer is one electrode and the backside isthe other electrode. The process for forming such a battery may useeither a stop layer during Si etch or a backside thinning process withstop on the bottom electrode. The combination of many of these Batteries(battery elements) to one Battery Package with higher current or highervoltage may be possible, for example.

FIG. 12 shows a flow chart of a method 1200 for forming a batteryelement according to an embodiment. The method 1200 comprises etching1210 trenches into a substrate and crystal orientation dependent etching1220 of the trenches. Further, the method 120 comprises forming 1230solid state battery structures within the trenches.

By using crystal orientation dependent etching, angular geometries ofthe trenches may be manufacturable or can be manufactured. Trenches withangular geometries may enable a very dense distribution or packing ofthe trenches. In this way, the power density of the battery element anda battery using such battery elements may be increased.

For example, a dry chemical etch process is used for the etching 1210 ofthe trenches into the substrate. The etching 1210 of the trenches maycomprise a substantially isotropic etching behavior. A mask may be usedto etch trenches at desired positions. By using a dry chemical etchprocess trenches with a high aspect ratio may be obtainable.

For example, a wet chemical etch process may be used for the crystalorientation dependent etching 1220. The crystal orientation dependentetching 1220 may comprise a substantially anisotropic etching behavior.In other words, the crystal orientation dependent etching 1220 maycomprise preferred etch directions along crystallographic directions ofthe substrate. Optionally, Potassium hydroxide KOH or ammonium hydroxideNH₄OH may be used for the crystal orientation dependent etching (e.g.,for a silicon substrate) or another liquid suitable for crystalorientation dependent etching of the material of the substrate.

The etching 1210 of the trenches may set a basic or general distributionof the trenches over the substrate. For example, the trenches may bedistributed over the substrate according to a hexagonal pattern or aquadratic pattern. In other words, centers of the geometry of thetrenches may be arranged on the grid points of a hexagonal or aquadratic grid, for example.

The crystal orientation dependent etching 1220 may adapt a geometry ofthe trenches caused by the previous etching (e.g., dry chemical) to adesired geometry. For example, the trenches may comprise a substantiallyrectangular lateral shape or quadratic lateral shape after the crystalorientation dependent etching 1220. In other words, a top view of atrench after crystal orientation dependent etching 1220 may comprisesubstantially rectangular shape or quadratic shape. For example, adeviation from the rectangular shape or quadratic shape may be less than10% (or less than 5% or less than 1%) of a lateral length or side lengthof the rectangular shape or quadratic shape.

For example, a very dense distribution may be used for the etching 1210of the trenches and the area wasted between the trenches may be furtherreduced by adapting the geometry of the trenches from a basicallyrounded geometry after etching 1210 the trenches to a basically angulargeometry after the crystal orientation dependent etching 1220.

FIG. 13a-c shows an example of a trench arrangement withcrystallographic etch process. FIG. 13a shows the substrate 1310 afterthe trench etch 1320 in a quadratic pattern 1330. A battery surface of ˜2πr˜6.2 r may be obtained. Afterwards, the geometry of the trenches isadapted to a substantially quadratic geometry 1340 by a crystaldependent etch as shown in FIG. 13b . The resulting silicon Si matrix isshown in FIG. 13c . A battery surface of ˜4*2r˜8 r may be obtained. Inthis way, the power density of the battery element may be increased.

FIG. 14a-c shows another example of a trench arrangement withcrystallographic etch process. FIG. 14a shows the substrate 1410 afterthe trench etch 1420 in a hexagonal pattern 1430. Afterwards, thegeometry of the trenches is adapted to a substantially rectangulargeometry 1440 by a crystal dependent etch as shown in FIG. 14b . Theresulting silicon Si matrix is shown in FIG. 14c . In this way, thepower density of the battery element may be increased.

More details and optional aspects of the method 1200 are described inconnection with the proposed concept or one or more embodiments (e.g.,FIG. 1-11) described above (e.g., substrate, dimension of trenches,solid state battery structure, electrodes, package).

For example, forming 1230 the solid state battery structures within thetrenches may comprise forming a solid state electrolyte layer between afirst electrode layer and a second electrode layer. The solid stateelectrolyte layer may comprise lithium phosphorus oxynitride. The firstelectrode layer may comprise an anode layer comprising carbon orsilicon. The second electrode layer may comprise a cathode layercomprising lithium cobalt oxide and a collector layer comprising titannitride.

For example, the trenches reach deeper into the substrate than 500 μm.The trenches may comprise an aspect ratio larger than 10. The trenchesmay comprise a maximal width of less than 300 μm. The trenches maycomprise a distance to each other between 2 μm and 300 nm. The trenchesmay comprise a maximal depth larger than a maximal lateral dimension.

For example, the substrate may be substantially a complete wafer. FIG.15 shows a schematic illustration of a trench arrangement on a wafer1500 for a wafer battery comprising trenches distributed over the wafer1500 according to a hexagonal arrangement 1510 or a quadraticarrangement 1520.

FIG. 16a-b show a schematic illustration of a battery element 1600according to an embodiment. The battery element 1600 comprises asubstrate 1610 with a plurality of trenches 1620 reaching from a surfaceof the substrate 1610 into the substrate 1610. At least a part of eachtrench 1620 of the plurality of trenches 1620 is filled with a solidstate battery structure 1630. The trenches 1620 of the plurality oftrenches 1620 comprise a substantially rectangular shape or quadraticshape at the surface of the substrate 1610.

By implementing trenches with a rectangular shape or quadratic shape, avery dense distribution or packing of the trenches may be achievable. Inthis way, the power density of the battery element and a battery usingsuch battery elements may be increased.

More details and optional aspects of the battery element 1600 aredescribed in connection with the proposed concept or one or moreembodiments (e.g., FIG. 1-15) described above (e.g., substrate,dimension of trenches, solid state battery structure, electrodes,package, shapes, distribution patterns). In other words, the batteryelement 1600 may comprise one or more optional additional featurescorresponding to one or more aspects described in connection with theproposed concept or one or more embodiments (e.g., FIG. 1-15) describedabove.

For example, the battery element 1600 may comprise a first batteryelement electrode electrically connected to a first electrode of thesolid state battery structures 1630 within the plurality of trenches1620 and a second battery element electrode electrically connected to asecond electrode of the solid state battery structures 1630 within theplurality of trenches 1620.

Optionally, the substrate 1610 is at least more than half of a wafer,for example.

FIG. 17 shows a schematic cross section of a battery 1700 according toan embodiment. The battery 1700 comprises a plurality of wafers 1710arranged in a stacked manner. Each wafer 1710 comprises batterystructures.

By stacking a plurality of wafers with battery structures arrangedwithin trenches, a battery providing a desired voltage or desiredcapacity may be feasible. The battery elements may be stacked with loweffort. In this way, a battery with high power density may be provided.

Optionally, the battery structures may be solid state batterystructures. Alternatively, the battery structures may be polymer batterystructures or gel battery structures, for example.

Optionally, the battery structures may be arranged within trenchesreaching into the respective wafer. Alternatively, the batterystructures may be deposited on a substantially flat surface of therespective wafer, for example.

The stack of wafers 1710 may be arranged within a package 1720 of thebattery 1700. At least two externally accessible battery electrodes 1730may reach through the package 1720 to provide a battery voltage to anexternal device.

More details and optional aspects of the battery 1700 are described inconnection with the proposed concept or one or more embodiments (e.g.,FIG. 1-16) described above (e.g., substrate, dimension of trenches,solid state battery structure, electrodes, package). In other words, thebattery 1700 may comprise one or more optional additional featurescorresponding to one or more aspects described in connection with theproposed concept or one or more embodiments (e.g., FIG. 1-16) describedabove.

Some embodiments relate to a wafer battery with high energy density. Aproposed battery design may enable to get a high or the highest possibleenergy density.

In contrast to multiple stacking of laminates, e.g., on a role, wherethe resistance of one electrode layer is increased with the number ofstacked laminates on the role, a 3-dimensional structure on a wafermatrix is proposed as silicon-based wafer battery (e.g., with twoelectrode on both sides of the wafer), for example. The battery layerscan be arranged 3-dimensional. In this case, the surface for thebattery-layers may be increased or maximized, for example.

For example, it is proposed to use crystal oriented Si-etchingtechniques to achieve a low or minimum silicon matrix volume for high ormaximum battery laminate surface. For example, KOH or NH₄OH or othercrystal dependent etches may be used to form a grid of Silicon as matrixfor the battery layer depositions.

A proposed battery may be formed with a wafer, where the Si matrix ismodified by crystal-oriented etch processes to form a high or maximum ofsurface with low or a minimum of stable Silicon volume.

A dense or optimum arrangement of trenches on the surface of the waferbattery may be either hexagonal or quadratic, for example.

With crystallographic etches, the battery layer surface may be increasedwithout changing the minimum thickness between two trenches and withoutchanging the wafer size by more than 20%, for example. In someapplications, the power density is not sacrificed, for example.

Example embodiments may further provide a computer program having aprogram code for performing one of the above methods, when the computerprogram is executed on a computer or processor. A person of skill in theart would readily recognize that steps of various above-describedmethods may be performed by programmed computers. Herein, some exampleembodiments are also intended to cover program storage devices, e.g.,digital data storage media, which are machine or computer readable andencode machine-executable or computer-executable programs ofinstructions, wherein the instructions perform some or all of the actsof the above-described methods. The program storage devices may be,e.g., digital memories, magnetic storage media such as magnetic disksand magnetic tapes, hard drives, or optically readable digital datastorage media. Further example embodiments are also intended to covercomputers programmed to perform the acts of the above-described methodsor (field) programmable logic arrays ((F)PLAs) or (field) programmablegate arrays ((F)PGAs), programmed to perform the acts of theabove-described methods.

The description and drawings merely illustrate the principles of thedisclosure. It will thus be appreciated that those skilled in the artwill be able to devise various arrangements that, although notexplicitly described or shown herein, embody the principles of thedisclosure and are included within its spirit and scope. Furthermore,all examples recited herein are principally intended expressly to beonly for pedagogical purposes to aid the reader in understanding theprinciples of the disclosure and the concepts contributed by theinventor(s) to furthering the art, and are to be construed as beingwithout limitation to such specifically recited examples and conditions.Moreover, all statements herein reciting principles, aspects, andembodiments of the disclosure, as well as specific examples thereof, areintended to encompass equivalents thereof.

Functional blocks denoted as “means for . . . ” (performing a certainfunction) shall be understood as functional blocks comprising circuitrythat is configured to perform a certain function, respectively. Hence, a“means for s.th.” may as well be understood as a “means configured to orsuited for s.th.”. A means configured to perform a certain functiondoes, hence, not imply that such means necessarily is performing thefunction (at a given time instant).

Functions of various elements shown in the figures, including anyfunctional blocks labeled as “means”, “means for providing a sensorsignal”, “means for generating a transmit signal.”, etc., may beprovided through the use of dedicated hardware, such as “a signalprovider”, “a signal processing unit”, “a processor”, “a controller”,etc. as well as hardware capable of executing software in associationwith appropriate software. Moreover, any entity described herein as“means”, may correspond to or be implemented as “one or more modules”,“one or more devices”, “one or more units”, etc. When provided by aprocessor, the functions may be provided by a single dedicatedprocessor, by a single shared processor, or by a plurality of individualprocessors, some of which may be shared. Moreover, explicit use of theterm “processor” or “controller” should not be construed to referexclusively to hardware capable of executing software, and mayimplicitly include, without limitation, digital signal processor (DSP)hardware, network processor, application specific integrated circuit(ASIC), field programmable gate array (FPGA), read only memory (ROM) forstoring software, random access memory (RAM), and non-volatile storage.Other hardware, conventional and/or custom, may also be included.

It should be appreciated by those skilled in the art that any blockdiagrams herein represent conceptual views of illustrative circuitryembodying the principles of the disclosure. Similarly, it will beappreciated that any flow charts, flow diagrams, state transitiondiagrams, pseudo code, and the like represent various processes whichmay be substantially represented in computer readable medium and soexecuted by a computer or processor, whether or not such computer orprocessor is explicitly shown.

Furthermore, the following claims are hereby incorporated into thedetailed description, where each claim may stand on its own as aseparate example embodiment. While each claim may stand on its own as aseparate example embodiment, it is to be noted that—although a dependentclaim may refer in the claims to a specific combination with one or moreother claims—other example embodiments may also include a combination ofthe dependent claim with the subject matter of each other dependent orindependent claim. Such combinations are proposed herein unless it isstated that a specific combination is not intended. Furthermore, it isintended to include also features of a claim to any other independentclaim even if this claim is not directly made dependent to theindependent claim.

It is further to be noted that methods disclosed in the specification orin the claims may be implemented by a device having means for performingeach of the respective acts of these methods.

Further, it is to be understood that the disclosure of multiple acts orfunctions disclosed in the specification or claims may not be construedas to be within the specific order. Therefore, the disclosure ofmultiple acts or functions will not limit these to a particular orderunless such acts or functions are not interchangeable for technicalreasons. Furthermore, in some embodiments a single act may include ormay be broken into multiple sub acts. Such sub acts may be included andpart of the disclosure of this single act unless explicitly excluded.

What is claimed is:
 1. A battery element comprising: a substrate with aplurality of trenches extending into the substrate, wherein at least apart of each trench of the plurality of trenches is filled with a solidstate battery structure; a front side battery element electrode arrangedat a front side of the substrate and electrically connected within theplurality of trenches to a first electrode layer of the solid statebattery structures; and a backside battery element electrode arranged ata backside of the substrate and electrically connected to a secondelectrode layer of the solid state battery structures within theplurality of trenches, wherein the front side battery element electrodeis separated from the backside battery element electrode by at least thesolid state battery structures, wherein the trenches of the plurality oftrenches extend from the front side of the substrate to the backside ofthe substrate, and wherein the solid state battery structures extendfrom the front side of the substrate to the backside of the substratewithin the trenches.
 2. The battery element of claim 1, wherein thefront side battery element electrode extends along at least a half ofthe front side of the substrate.
 3. The battery element of claim 1,wherein the backside battery element electrode extends along at least ahalf of the backside of the substrate.
 4. The battery element of claim1, wherein the front side battery element electrode and the backsidebattery element electrode comprise copper.
 5. The battery element ofclaim 1, wherein the solid state battery structures within the trenchescomprise a solid state electrolyte layer between the first electrodelayer and the second electrode layer.
 6. The battery element of claim 5,wherein the solid state electrolyte layer comprises lithium phosphorusoxynitride.
 7. The battery element of claim 4, wherein the firstelectrode layer comprises an anode layer comprising carbon or silicon.8. The battery element of claim 4, wherein the second electrode layer ofthe solid state battery structures is located between the firstelectrode layer of the solid state battery structures and the backsidebattery element electrode at the backside of the substrate.
 9. Thebattery element of claim 1, wherein the substrate comprises a thicknessof more than 500 μm.
 10. The battery element of claim 1, whereintrenches of the plurality of trenches comprise an aspect ratio largerthan
 10. 11. The battery element of claim 1, wherein trenches of theplurality of trenches comprise a maximal width of less than 300 μm. 12.The battery element of claim 1, wherein a distance between adjacenttrenches of the plurality of trenches is between 2 μm and 300 nm. 13.The battery element of claim 1, wherein at least a portion of the solidstate battery structure contacts walls within each trench of theplurality of trenches.
 14. The battery element of claim 1, wherein thesubstrate is a wafer.
 15. The battery element of claim 1, wherein thefront side battery element electrode is electrically connected withinthe plurality of trenches in a continuous manner.
 16. A batterycomprising a plurality of battery elements arranged in a stacked manner,wherein each battery element comprises: a substrate with a plurality oftrenches extending into the substrate, wherein at least a part of eachtrench of the plurality of trenches is filled with a solid state batterystructure; a front side battery element electrode arranged at a frontside of the substrate and electrically connected within the plurality oftrenches to a first electrode layer of the solid state batterystructures; a backside battery element electrode arranged at a backsideof the substrate and electrically connected to a second electrode layerof the solid state battery structures within the plurality of trenches;and an electrolyte between the first and second electrode layers for ionconductivity between the first and second electrode layers, wherein thefront side battery element electrode is separated from the backsidebattery element electrode by at least the solid state batterystructures, wherein the trenches of the plurality of trenches extendfrom the front side of the substrate to the backside of the substrate,and wherein the solid state battery structures extend from the frontside of the substrate to the backside of the substrate within thetrenches.
 17. A method for forming a battery, the method comprising:etching trenches into a substrate; forming a solid state batterystructure within the trenches; forming a front side battery elementelectrode arranged at a front side of the substrate and electricallyconnected within the trenches to a first electrode layer of the solidstate battery structure; thinning the substrate from a backside of thesubstrate after forming the solid state battery structure within thetrenches until the solid state battery structure is uncovered at thebackside of the substrate; forming a backside battery element electrodearranged at a backside of the substrate and electrically connected to asecond electrode layer of the solid state battery structure within thetrenches; and providing an electrolyte between the first and secondelectrode layers for ion conductivity between the first and secondelectrode layers, wherein the front side battery element electrode isseparated from the backside battery element electrode by at least thesolid state battery structures.
 18. The method of claim 17, furthercomprising stacking a plurality of battery elements so that electrodesof neighboring battery elements are in contact with each other.